An innovative control method for adjusting the capacitor bank voltage of the hybrid energy storage system for a PMSG based wind turbine

The increasing growth of wind power plants has resulted in an increase in their impact on the stability of the power system. In this case, for ensuring the grid stability, these resources must inject an almost constant power into the grid. One way to produce a constant power is to use a hybrid energy storage system. In this method, the maximum power is obtained from the wind. The smoothed power is delivered to the grid and the fluctuations are compensated by the energy storage system. One of the challenges in this method is that during the control by compensating the power fluctuations by means of the energy storage system, the energy level of these resources varies. The other challenge is to extend the energy storage system lifetime during its operation to meet the needs of the power system. In this paper, a method is proposed to control the capacitor and the battery charge and discharge amount in a hybrid energy storage system. In this approach, by injecting the feed-forward current into the battery reference current, the capacitor voltage is regulated and by considering the battery condition, the feed-forward current is determined in a way that the capacitor voltage quickly reaches the ideal amount and also a current with high peak amount doesn't pass through the battery. In addition, the feed-forward current is adjusted in a way so that the unnecessary charge and discharges of the battery, which is resulted from the power division by the filter, are reduced. The functionality of the proposed method is shown in MATLAB software and Simulink environment.